SPN 4375 FMI 6 is the Detroit DD Series (EPA 2007–Current) diagnostic trouble code that Detroit documents as “Diesel Exhaust Fluid (DEF) Pump Supply Current High”. This 8-page EPA10 fault-code sheet documents the monitored DEF pump current parameter and the SCR air pressure test, the dash-lamp indication and engine reaction, and the ordered troubleshooting steps used to confirm and clear the condition. The monitored parameter is DEF pump supply current, the engine reaction is a 25% derate with the MIL and CEL on, and this eight-page procedure uses the SCR air pressure test and the DEF pump current graph to separate a pneumatic fault from an electrical one.
SPN 4375 FMI 6 document details
| Brand | Detroit (Detroit Diesel) |
|---|---|
| Model coverage | Detroit DD Series (EPA 2007-Current) engines |
| System / group | DD Series (EPA 2007-Current) / DTCs |
| Publication / source | Detroit Power Service Literature (TruckFaultCodes reference, 2017) |
| Emissions family | EPA10 |
| Pages | 8 |
| File size | 0.55 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code description and monitored parameters
- SCR air pressure test and DEF pump current graph
- DEF pressure versus ambient air pressure check
- Pressure Limiting Unit air-line routing inspection
- DEF pump resistance measurement
- DEF pump harness voltage checks
- DEF quantity test verification
Applicable truck models
This fault-code procedure applies to trucks powered by the Detroit DD Series (EPA 2007-Current) engines on the DD Series (EPA 2007–Current) platform. The technician runs the Selective Catalytic Reduction air pressure test, graphs DEF pump current, compares DEF pressure to ambient and DEF air pressure, checks the Pressure Limiting Unit air-line routing and vehicle air above 100 psi, measures DEF pump resistance against 400 ohms, verifies the harness voltages to the ACM2 120-pin connector, and confirms delivery with the DEF quantity test. Always confirm the engine family and EPA10 emissions level against the vehicle, and cross-check the latest procedure in the Detroit Power Service Literature on the official Detroit website.
Who needs this SPN 4375 FMI 6 manual
Diesel technicians, fleet maintenance teams and workshop owners diagnosing a high DEF pump supply current, a 25% derate or an SCR dosing fault on Detroit DD Series trucks use this sheet to work the fault in order instead of guessing. Because the cause can be pneumatic or electrical, the graphed air-pressure test in this sheet is what separates a bad pump from a bad air supply or pressure sensor.
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